(Hive Bee)
06-04-02 21:40
No 317594
      benzaldehydes from benzyl alcohols
(Rated as: excellent)

piperonyl alcohol --> piperonal
MnO2, molecular sieves, hexane, 2h
"... the hydrolytically labile methylenedioxy linkage in 1l survived,
giving piperonal 2l, an important fragrance and a synthetic precursor
..., in quasiquantitative yield."
journal of chemical research (synopses), 1998 (6), 308-309
"oxidation by chemical manganese dioxide.
part 1. facile oxidation of benzylic alcohols in hexane"
masao hirano, sigetake yakaba, hideki chikamori,
james h. clark, takashi morimoto
abstract: an inexpensive, stable, commercially available reagent, chemical
manganese dioxide, can be used for the oxidation of a wide variety of
benzylic alcohols and the C-C bond cleavage of aromatic diols in hexane
under relatively mild conditions.

piperonyl alcohol --> piperonal
MnO2(CMD), CH2Cl2, ambient temperature, 24h, yield 95%
synlett, 1998 1, 35-36
"chemical manganese dioxide (CMD), an efficient activated manganese
dioxide. application to oxidation of benzylic and allylic alcohols"
toyohiko aoyama, naoko sonoda, mariko yamauchi, kyoko toriyama,
masahiro anzai, akira ando, takayuki shioiri
abstract: oxidation of benzylic and allylic alcohols with chemical manganese
dioxide smoothly proceeded under mild reaction conditions to give the
corresponding aldehydes and ketones, respectively, in high yields.

piperonyl alcohol --> piperonal
CH2Cl2, 3h, yield 96%
j chem soc dalton trans, 1989, 901-906
ahmed m el-hendawy, william p griffith, fatma i taha, mahmoud n moussa

piperonyl alcohol --> piperonal
H2O2, ligninase(catalyst), ambient temperature,
pH 3.0, subject studied, product distribution
phytochemistry, 1991 30 1, 121-126
agnes ageorges, andrew pelter, robert s ward

4-methoxybenzyl alcohol --> anisaldehyde
KMnO4, 45min, yield 95% (reaction 14 on page 5834)
tetrahedron letters, 2001 42, 5833-5836
"solvent free permanganate oxidations"
ahmad shaabani, donald g lee
abstract: the oxidations of organic compounds by permanganate under solvent free con-
ditions have been studied. thiols and primary aromatic amines undergo oxidative coupling
reactions to give disulfides and diazenes, respectively, sulfides are oxidized to sulfones,
primary and secondary alcohols are converted to aldehydes and ketones, 1,4-diols and
cyclic ethers give lactones and arenes are oxidized to the corresponding alpha-ketones.
the experimental procedure is simple and the products are easily isolated in good yields.
../rhodium/pdf /solventfree.kmno4.oxidation.pdf

benzyl alcohols --> benzaldehydes
synthetic communications, 2001 31(9), 1389-1397
mohammed hashmat ali, candace j wiggin
abstract: Jones reagent supported on silica gel (SJR) has been used for
oxidation of benzyl alcohols to the corresponding benzaldehydes in high yields
utilizing organic solvent. This newly developed reagent is easy to prepare and
use. SJR is also safer than the traditional Jones reagent.

benzyl alcohol --> benzaldehyde
silica gel supported ferric nitrate reagent, hexane, heating, 4h
synth commun, 1998 28 2, 207-212; bhushan khadilkar, shobha borkar

benzyl alcohol --> benzaldehyde
tetrahedron letters, 1997 38(45), 7823-7824
"active manganese dioxide on silica: oxidation of alcohols
under solvent-free conditions using microwaves"
rajender s.a varma, rajesh k.a saini, rajendera dahiya
abstract: alcohols are rapidly and selectively oxidized to the corresponding
carbonyl compounds by silica supported active manganese dioxide under
solvent-free conditions using microwaves.
../rhodium/pdf /mw.mno2.benzaldehyde.pdf

benzyl alcohol --> benzaldehyde
MnO2/bentonite, chromat, irradiation, 175C, 1min, yield 40%
tetrahedron lett, 1993 34 33, 5293-5294
luis a martinez, olivia garcia, francisco delgado, cecilio alvarez, rocio patino

benzyl alcohol --> benzaldehyde
manganese dioxide, turnov, hexane, 20C, yield 60%
j chem soc perkin trans 1, 1990 7, 1937-1943
jose a s cavaleiro, maria g p s neves, michael j e hewlins, anthony h jackson

benzyl alcohol --> benzaldehyde
HBr, H2O2, CH2Cl2, 60C, 4h, yield 84%
bull soc chim fr, 1988 4, 756; jihad dakka, yoel sasson
(Hive Bee)
06-05-02 09:21
No 317758
      More refs  Bookmark   

While we're at it I may as well add the following refs on MnO2 oxidns:

* I.M. Goldman, J. Org. Chem.,34 (1969) 1979

* A. J. Fatiadi, Synthesis, 1976, 65

(I haven't looked at any of these so I dunno if they're any good)
03-17-03 23:24
No 418170
      Reference Help  Bookmark   

Can someone give me or tell me where to find this ref:

piperonyl alcohol --> piperonal
CH2Cl2, 3h, yield 96%
j chem soc dalton trans, 1989, 901-906
ahmed m el-hendawy, william p griffith, fatma i taha, mahmoud n moussa

 It would be better if someone just gave me the searchable database link so I could look them up on my own. Thanks

(Chief Bee)
03-18-03 23:10
No 418793
      refs  Bookmark   

tryptamine_king: I don't think you want that one, it is about making exotic Rhenium/Cymene ligands, and then use them for dehydrogenation of alcohols to aldehydes.
03-19-03 07:13
No 418943
      Thank you sir  Bookmark   

>tryptamine_king: I don't think you want that one, it is >about making exotic Rhenium/Cymene ligands, and then use >them for dehydrogenation of alcohols to aldehydes.

thank you sir, you have saved this new bee's ass. I read the ref you mentioned and it looked great. im just beginning in chem and I could understand everything discussed in it. hell yeah. thanks again.

(Hive Adickt)
03-19-03 16:26
No 419071
      oxidation  Bookmark   

Iff you ask mee, the one and only way to convert bezylic alcohol to aldehyde is with MnO2, easy, yeald kvatitative and only OTC chemical's are used.
03-20-03 04:15
No 419257
      IBX  Bookmark   

If IBX (o-iodoxy benzoic acid) can be had, it is the best.  Simply heat in EtOAc @ 95 deg C for 3 hours of so depending on the alcohol and you just have to cool, filter IBX and evaporate solvent to get your aldehyde in extremely high yields (80-98%). 
This works for substituted benzyl alcohols (piperonyl alcohol and such...) but not benzyl alcohol itself.  In that case, it makes benzoic acid , but for the most part it will work on any other benzyl alcohol. 

respect... smile